/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.drools.ruleunits.impl.factory;

import java.util.HashMap;
import java.util.Map;

import org.drools.ruleunits.api.RuleUnit;
import org.drools.ruleunits.api.RuleUnitData;
import org.drools.ruleunits.api.RuleUnitInstance;
import org.drools.ruleunits.api.RuleUnits;

public abstract class AbstractRuleUnits implements RuleUnits {

    private Map<String, RuleUnitInstance<?>> unitRegistry = new HashMap<>();

    @Override
    public <T extends RuleUnitData> RuleUnit<T> create(Class<T> clazz) {
        return (RuleUnit<T>) create(clazz.getCanonicalName());
    }

    protected abstract RuleUnit<?> create(String fqcn);

    @Override
    public void register(String name, RuleUnitInstance<?> unitInstance) {
        if (name == null) {
            throw new IllegalArgumentException("Cannot register a RuleUnitInstance with a null name");
        }
        unitRegistry.put(name, unitInstance);
    }

    @Override
    public RuleUnitInstance<?> getRegisteredInstance(String name) {
        return unitRegistry.get(name);
    }


    public static class DummyRuleUnits extends AbstractRuleUnits {

        public static final DummyRuleUnits INSTANCE = new DummyRuleUnits();

        @Override
        protected RuleUnit<?> create(String fqcn) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void register(RuleUnit<?> unit) {
            // ignore
        }
    }
}
